The test signals of various channels of a multiple channel tester can have different propagation delays associated with the different paths from the common clock driving all channels of the tester to the outputs of the drivers. To guarantee that the drivers for the various channels operate synchronously under the various operating conditions, adjustable delays have been provided for the different paths to the drivers in some multiple channel testers. The adjustments often are made at the beginning of a new eight-hour shift, as there is a tendency for the propagation delays to change with time. A method of measuring delays associated with the different paths that has been used is the time domain reflection technique, requiring averaging of plural measurements to offset random jitter owing to noise.